Agricultural machines, in particular haymaking machines, are often provided with movable, especially rotatable, rams on which coil springs are located from which springs, prongs or tines extend to engage swaths or layers of cut crop, such as grass, clover and the like, lying on the ground.
The prongs are arranged and moved to spread or scatter and expose to sun the swaths or to collect the crop material. From time to time, the prongs can hit a stone and may be broken off. If a piece of a metal prong detaches from the spring, it is very difficult and even impossible to find it in a crop such as hay. Such a piece of hard metal may then damage other agricultural machines, such as hay or fodder pick-up or baling and chopping implements or can even harmfully wound cattle when swallowed.
Mostly such a rupture of the prong occurs at the region of transition between the coil of the spring and the tine. Thus, a long piece of metal can become intermingled with the crop material. There already have been various attempts to eliminate this danger by preventing broken off portions of the prongs or tines from detaching from the machine. One of these attempts has consisted in attaching to the end of the prong a wire and anchoring the other end of this wire on the arm carrying the coil spring with the prongs. Upon the breaking-off of a piece of one of the prongs, this piece remained attached to a member of the machine and could not be lost.
However, this arrangement proved to have the shortcoming that the broken-off piece in a haymaking machine where the carrying arm is rotated was also swung about and collided with various adjacent parts of the machine and damaged them. The rapid rotation of such a metallic piece and its swinging on a wire could also seriously injure the machine operator, especially on breakage of the wire.
Another proposal for avoiding and setting apart any such danger was in German Utility Model (Gebrauchsmuster) GMB 7 319 115. Here, the individual prongs are clad with a separate and flexibly formed hose (tube) covering the predominant portion of the prong nearly up to the coil winding of the spring. The short pieces of a hose used for this purpose have a diameter smaller than that of the prongs. Due to this difference in the diameter, the hose pieces, after being pulled over the prongs strongly adhere to the latter. The neighboring hose pieces also were interconnected by lashing. The mutual connection of the pair of adjacent prongs maintained the prong spring power important for effective machine operation and prevented an uncontrolled detachment of a broken-off piece of a prong. However, this also had the drawback that the hose pieces were kept on the prongs by squeezing engagement which created difficulties during the mounting of these hose pieces. However, even greater difficulties were those connected with the detachment and separation of such hose pieces from the prongs. These difficulties met both during mounting and dismounting of these hose pieces created significant problems, so that reuse of of such springs and prongs was almost impossible or required an unreasonably long time for the replacement.